LBANY -- In late February, a sea of several thousand gun-rights supporters stood on the state Capitol's west lawn. While waving American flags and "Don't Tread on Me" banners, they chanted over and over: "We will not comply."

Starting this week, their message will be put to the test.

Monday marks a key date in the ongoing battle over the state's controversial gun-control laws. A much-debated provision of the Secure Ammunition and Firearms Enforcement Act takes effect, prohibiting firearm owners from loading more than seven rounds into their magazines unless they're at a range or in competition.

Also on Monday, owners of certain AR15 assault rifles and other semi-automatic guns with military-style features -- the sale of which is now banned in New York -- can begin registering their firearms with the state and have a year to do so.

The form will be available on State Police's website beginning Monday, according to the agency. The registration requirement applies to anyone who owned such a gun before Jan. 15.

The provisions were among the hallmarks of the new law, which Gov. Andrew Cuomo shepherded through the Legislature in January as the state moved to become the first to enact new gun-control measures after the mass shooting in Newtown, Conn.

And as the law takes effect, gun owners will have one of their first chances to decide whether to comply -- or deliberately break it in protest.

"That's a personal decision that everyone has to make," said Tom King, president of the state Rifle & Pistol Association. "I personally believe that New Yorkers are legal and lawful gun owners and citizens of the state. And being legal and lawful, they will obey the law."

The magazine limit has already been scaled back since it was first enacted, though Cuomo has challenged that characterization. As part of budget negotiations last month, Cuomo and lawmakers agreed to continue to permit the sale of 10-round-capacity magazines but only allow them to be loaded with seven. The original law prohibited dealers from selling anything greater than seven-bullet magazines.